Keep an eye on all that leftover squash casserole and sweet potato souffle in the fridge. It would be a shame if it went bad, because Americans waste a staggering amount of food every year. Nearly 40 percent of the food supply is wasted in the United States alone, according to a new study, published in the journal PLoS ONE.

Researchers Kevin Hall and Carson Chow analyzed average body weight in the United States from 1974 to 2003 and figured out how much food people were eating during this period. Hall and Chow assumed that levels of physical activity haven’t changed; some researchers think that activity has decreased, but Hall and Chow say their assumption is conservative. Then they compared that amount with estimates of the food available for U.S. consumers, as reported by the U.S. government to the Food and Agriculture Organization of the United Nations. The difference between calories available and calories consumed, they say, is food wasted[ScienceNOW Daily News].They dubbed the difference the “missing mass of American food,” and say it’s the equivalent to each person in the United States wasting 1,450 calories-worth of food per day.

The new study reports more waste than a prior U.S. Department of Agriculture study which found that 27 percent of the food produced in the United States is wasted, according to their interviews with consumers and producers. A similar study presented over the summer suggestsas much as 30 percent of food, worth about $48.3 billion, is tossed out each year, according to … the Stockholm International Water Institute (SIWI), the Food and Agriculture Organization of the United Nations (FAO) and the International Water Management Institute (IWMI) [LiveScience].However, all the food waste studies seem to agree that while poorer countries waste food due to inefficient agricultural production, the majority of waste in richer countries is attributed to consumers simply tossing out the food they buy but don’t eat. An overall decline in food prices in rich countries has also made leftovers seem less desirable and more expendable.